(1) Field of the Invention
This invention relates to an N-(2-chloro-4-nitrophenyl)-benzenesulfonamide derivative represented by the following general formula (I): ##STR2## wherein X and Y individually mean a hydrogen or chlorine atom and Z denotes a chlorine atom or trifluoromethyl group, and an agricultural fungicide containing said derivative as an active ingredient.
The above compound of this invention is useful as a soil fungicide for agriculture.
(2) Description of the Prior Art
Crop diseases have remained to date as one of serious problems for the cultivation of crops. Among such diseases, soil-borne diseases induced by pathogenic fungi in the soil (hereinafter called merely "soil-borne diseases" for the sake of brevity) are one of problems which are particularly difficult to solve. Recently, there are ever-increasing tendencies that vegetable culture areas are limited to certain specific districts and the same crops of commerce are cultivated continuously. For these tendencies, it has become more and more important to control such soil-borne diseases. It is however extremely difficult to control soil-borne diseases due to their nature. They hence tend to give more and more damages. For example, PCNB (pentachloronitrobenzene) has been used in some countries as a breakthrough fungicide against clubroot of cruciferous vegetables such as cabbages, Chinese cabbages, turnips, cauliflowers, broccolies and the like. It is applied so much that its application rate is said to be equivalent to fertilizers. In fields where cruciferous vegetables have been cultivated continuously, the standard application rate for PCNB is not enough to draw out its effects to satisfactory extents and it has hence become a common practice to apply in PCNB in much greater amounts. On the other hand, the environmental contamination by agricultural chemicals has staged up to a social problem and chemicals, which are being used in such large volumes as PCNB, would no longer be allowed. There is thus an extremely strong demand for chemicals which can exhibit their effects at lower application rates. It has virtually been considered to be difficult to achieve perfect chemical control on other soil-borne diseases, for example, powdery scab and scab of potatoes, rhizomania of sugar beets, virus diseases of small grains transmitted by Polymyxa, lettuce big vein, a soil-borne disease of radish, turnips, sugar beets, peas and the like, induced by various Aphanomyuces. Numerous sulfonamide-type compounds have been synthesized for many years and many researches have been conducted on their physiological activities. In the agricultural field, researches have been made on their applications as insecticides, no say nothing of their applications as herbicides and fungicides. For example, Japanese Patent Publication Nos. 29571/1964 and 19199/1965 may be referred to in connection with their applications as herbicides. As fungicides, may be mentioned Japanese Patent Publication Nos. 9304/1969, 6836/1970, 6797/1971 and 15119/1972, Japanese Patent Laid-Open No. 31655/1982, U.S. Pat. Nos. 4,497,828 and 4,551,478 and so on. On the other hand, U.S. Pat. No. 3,034,955 may be referred to regarding their applications as insecticides.
Compounds of the following formula are disclosed in U.S. Pat. No. 3,034,955. ##STR3## In the above formula, Ar.sup.1 and Ar.sup.2 are recited individually as a phenyl group which contains one or more substituents selected from hydrogen and halogen atoms and trifluoromethyl, nitro, alkyl and alkoxy groups. However, none of the compounds of this invention are included in the specific exemplary compounds disclosed in the specification of the U.S. patent. Further, this prior art publication refers merely to insecticidal activities of these compounds and contains no disclosure as to their use as fungicides. Although the compounds of this invention fall under the generic concept defined by the general formula of U.S. Pat. No. 3,034,955, the present invention is limited specifically to the N-(2-chloro-4-nitropheyl)-benzenesulfonamide derivatives of the specific structure indicated by the above general formula (I). Incidentally, the above prior art publication discloses 3-trifluoromethyl-4-chlorobenzene sulphonic acid-2'-nitro-4'-trifluoromethyl anilide [N-(2-nitro-4-trifluoromethylphenyl)-4-chloro-3-trifluoromethylbenzenesulf onamide]as a nitro group-containing compound. This compound is however apparently different from the compounds of this invention.
In U.S. Pat. Nos. 4,497,828 and 4,551,478, there are disclosed the controlling effects of certain sulfonamide derivatives against club root of cruciferous vegetables. All of the compounds disclosed in these U.S. patents are however limited to 3-nitrobenzenesulfonamide derivatives and the compounds of this invention are not disclosed at all. Moreover, the compounds of this invention are far superior to the compounds disclosed in the above U.S. patents in their controlling effects against clubroot.
The rest of the above-mentioned prior art publications neither disclose nor suggest the application of the compounds of this invention as soil fungicides.